Draft gear



K. G. EMPSON DRAFT GEAR 3 Sheets-Sheet 1 Filed April 12. 1962 N 0 N -M-HHI H mm N E Q Q I m It 1 T11 I N Q 6 mm N2 3 wm M 9 f f K F 1 y W L June 2, 1964 EMPSQN 3,135,394

' DRAFT GEAR Filed April 12, 1962 3 Sheets-Sheet 2 F I I5- B INVENTOR 74 KENNETH G. E MPSON BY 50%;; 4* 5M ATTORNEYS June 2, 1964 K. e. EMPSON 3,135,394

DRAFT GEAR Filed April 12, 1962 3 Sheets-Sheet 3 INVENTOR. KENNETH G. EMPSON ATTORIVE V5 United States Patent 3,135,394 DRAFT GEAR Kenneth G. Empsou, San Jose, Calif, assignor to United Centrifugal Pumps, a corporation of California Filed Apr. 12, 1962, Ser. No. 186,923 2 Claims. (Cl. 213-43) This invention relates to a draft gear for use with a railroad coupler and more particularly relates to a combination of rubber spring and hydraulic draft gear which will fit into the pocket of the yoke of a railroad car.

It is an object'of the present invention to provide a draft gear with a rubber spring portion wherein the buff and draft strokes can be individually varied.

Another object of this invention is to provide a draft gear having a combination of rubber springs on both sides ofa hydraulic cylinder wherein the rubber springs give 'maintain control over the springs so that recoil is reduced to a fast but smooth return to a center position.

In accordance with one embodiment of the invention a draft gear is provided having a piston containing pressure sensitive valves which have a variable orifice so that the amount of restriction is automatically proportional to the force of the impact.

A further object of this invention is to provide a hydraulic draft gear having a relatively low hydraulicpressure due to its large piston area so that the. seals have along life.

A still further object of this invention is to provide a draft gear which can be shipped in precompressed form so that it will easily fit into the pocket of a railroad coupler yet upon the first impact will release to take up fully the space within the coupler so that there is no play in the system.

Other objects will be apparent from the specification which follows.

' In the drawings forming a part of this application:

FIGURE 1 is a plan view of a railroad coupler with the upper. structure removed with the draft gear of the present invention in place therein.

FIGURE 2 is a side sectional view of the coupler of FIGURE 1 on the lines 22 of FIGURE 1.

FIGURE 3 is a perspective view of the draft gear of the present invention with certain parts cut away to show the internal structure.

FIGURE 4 is an enlarged partial sectional view of a piston embodying a valve which may be used in connection with the draft gear of the present invention.

FIGURE 5 is a perspective view of a rubber draft spring and associated carrier plate and spacer plate.

FIGURE 6 is a sectional view through the spring of FIGURE 5 on the lines 6-6 of FIGURE 5.

FIGURE 7 is a perspective view of a rubber buff spring together with its associated carrier plate and spacer plate.

FIGURE 8 is a sectional view of the spring of FIGURE 7 on the lines 8-8 of FIGURE 7 Turning now to a description of the drawings by reference characters there is shown in FIGURES 1 and 2 a center sill 12 which forms a part of the frame of a railroad car having an abutment 14 which limits the contraction of the draft gear in the event of a failure of the cushioning device. The sill is provided with front stops 3,135,394 Patented June 2, 1964 16 and rear stops 18 which form a pocket for the reception of the draft gear which has been generally designatedZt). Within the pocket is a yoke generally'designated 22 having a top member 24, a bottom member 26 and a rear end member 28. The yoke 22 extends forward and terminates in ears, 30 and 32 which has a slot therein adapted to receive a conventional key 34. Extending forward from the coupler is a draft bar 36 terminating in a usual coupler arrangement 38, said draft bar having an elongated slot therein which passes over the key 34. It will be apparent from the structure thus far described that as a car is pulled in draft the key 34 will engage the rear of the slot 40, tending to pull the yoke forward, tending to compress the draft gear 20, pressing it against the shoulder 16 and thus transmitting the forward motion to the car. On the other hand, during coupling or stopping, the draft bar 36 will not transmit its force through the yoke because of the lost motion provided by the slot 40 and the draft bar will be pressed against the draft gear 2t), transmitting the force through the draft gear and to the rear stops 18.

The structure of the draft gear of the present invention itself is best seen in FIGURE 3 with certain parts shown in FIGURES 5 through 8. Referring now to these figures, thedraft gear of the vpresent invention comprises a box-like center member 42 having side arms 44 and 46 extending therefrom as shown. End plates 48 and 50 are provided, the end plates normally being adapted to slide freely within the side arms 44 and 46. In the center member 42 a hydraulic cylinder generally designated 52 is formed with a piston 54 therein having rigid piston rods 56 and 58 extending from each side thereof and through holes in the end plates 48 and 50. Preferably the rods are provided with end caps 60 and 62 as well as washers as at 64 so that the exact length of the rods can be adjustedby inserting or removing washers to compensate for slight manufacturing tolerances in railroad couplers. The cylinder 52 is filled with a fluid which is normally oil and both the cylinder 52 and the piston 54 may be made in various forms as is hereinafter explained in detail. The piston rods 56 and 58 pass through end 'walls .66 and 68 of the cylinder 52 and are provided with Hallprene fluid seals 7 0 and 72. Between the movable end plate 48 and the end plate 66 of the cylinder are the rubber buif springs 74 while similar rubber draft springs'76 are provided between the cylinder end 68 and the movable plate 50. The exact structure of these rubber springs. is best shown in FIGURES 5 through 8. The rubber springs comprise a metal plate 78 having the rubber spring element 80 and 82 formed on either side thereof. Preferably the metal plates 78 are perforated as at 84 so that the spring 80 and 82 can be molded on each side of the plate and join each other through the hole 84, producing the rigid structure shown. The draft springs proper comprise two segments designated 80A and 80B with a space 86 between the two. elements. Thus, as the rubber spring is compressed, the rubber can move sideways tosome extent both at the edges and into the spaceprovided at 86. Alternating with the plate 78 having the springs thereon are plain metal spacer plates 88. Of course, the metal plates could be formed with a spring on only one side thereof and the spacer plates dispensed with but the structure shown comprising alternate plain plates and plates having springs on both sides thereof makes for a stronger and more effective mechanical structure.

The buff springs shown in FIGURES 7 and 8 are quite similar to the draft springs described but here the spring outlet comprises a plurality of smaller rubber discs. The buff springs comprise metal plates 90 having the spring elements 92 and 94 on each side thereof. In this instance, the spring comprises three separate concentric rings 92A,

92B and ZC with spaces 96 and 98 therebetween. It is obvious that the buff springs will be more resilient than the draft springs heretofore described since the buff springs consist of smaller elements with more spaces between the elements. As before, plain metal spacer plates 1% are used between the element springs.

As was previously mentioned, the piston may or may not contain valves. Referring now specifically to FIG- URE 2, the piston 102 fits within a piston 104. The piston 162 has no openings therethrough but the cylinder 104 is tapered toward each end so that it forms an almost oiltight seal at the ends yet has a substantial clearance at the center. Thus the piston is relatively free to move near the center and the constriction becomes greater, and thus the resistance to movement, as the piston approaches the ends. On relatively light shocks, a light dampening action is developed, while on heavier shocks,

, a heavier dampening action is automaticallyproduced.

In some instances, it is desirable to provide a liner for the cylinder. This is perhaps best shown in FIGURES 3 and 4. Here the liner comprises two parts, namely, a forward part 106 and a rear part each of the liner parts having a series of slots 110 leading to a peripheral groove 112. The peripheral groove 112 is adjacent to a hole 114 normally closed by threaded plug 116 and enables all of the entrapped air to be bled from the system when the buffer is initially filled. In FIGURE 4, the taper of the liners 106 and 108 has been exaggerated for clarity. The advantages of the liner are that it is easier to machine than a relatively large cylinderand also liners of varying cylinder wall thickness and varying tapers can be inserted, depending on the exact service to which the device is to be placed.

As has been previously mentioned the piston may or may not be perforated. Thus, in the piston shown in FIGURE 2, there are no openings through the piston, control being exercised only by the double taper of the cylinder. In some instances, a more eflicient system is desired wherein more exact control can be exercised over the movement of the piston. For this purpose valve assemblies 118 may be provided in the piston. Referring now to FIGURE 4 showing an enlarged view of a suitable valve, the piston 120 is carried on the piston rod 122. The valve proper comprises two poppet valves 124 and126 adapted to seat on the seats 128 and 130 of the piston. The valves 124 and 126 are carried within the cylinder 132 on the sleeve 134 having attached thereto a piston 136 fitting withincylinder 138. The valve assembly is normally maintained in its center position by means of the springs 139. Ports 140 and 142 lead from one face of the piston 120 to the opposite side of the piston 136 so that as pressure is exerted on the face of one of the valves, tending to close it, an opposite counterbalancing pressure is provided on the piston 136, tending to keep it open. In actual practice, the area of the piston 136 ismade just slightly smaller than the area of the valve faces so that there will be a slight tendency of the valve to close. As pressure is built up on the coupler, pressure is built up on the valve face, but this pressure is largely counterbalanced by the force on the piston 136, so that the springs 139 can be relatively weak for the pressure involved. The eifect is that of a variable orifice which is large under conditions of low pressure but which decreases in size as the pressure increases until the valve completely closes at very high pressure. Thus, under light loads a large orifice is provided while under heavy loads a small orifice is provided.

Normally the rubber springs are used in sufficient numbers that they would press the ends 48 and 50 beyond the reach of the arms 44 and 46, making the device difii '4 cult to place in the yoke. This difiiculty can be solved by the use of shear pins 146 which extend from the arms into the end plates. These pins enable the device to be shipped and installed in precompressed condition. The first time the car is coupled and started these pins will shear oif, freeing the end plates.

It is believed apparent from the foregoing that I have provided a simple yet effective buffer forrailroad draft pocket being defined by side sills and foward and rear stops, said draft rigging including a yoke fitting around the draft gear and abutting on a rear element of the draft gear and said yoke being connected to a coupler whereby the back end of the coupler bears against an end of the draft gear in buff and whereby the yoke bears against the opposite end of the draft gear in draft, said draft gear comprising in combination:

(a) a box-like center member including a center member with side arms extending forward and to the rear of the central section,

(b) said side members lying between the sills, and the ends of said side members abutting the front and rear stops whereby the box-like member is restrained from substantial movement;

(0) an hydraulic cylinder in said central section;

(d) a piston in said cylinder;

(e) piston rods extending to the front and rear of said piston,

(f) one of said piston rods extending to the end of the yoke and the other of said piston rods extending to the back end of the coupler;

(g) rubber springs on both sides of the central member with the piston rods extending through the springs,

(h) said springs being located Within the space defined by the side members; and

(i) an end plate adjacent the outer end of each of the springs,

(j) said end plates being free to slide within the side members .but being restrained from movement beyond the ends of the side members,

(k) said side members serving as guides for the end plates,

(I) one of said end plates transmitting force to the rear of the coupler and the other of said end plates transmitting force to the yoke.

2. The structure of claim 1 wherein the piston is provided with valve openings having pressure responsive vales therein.

References Qited in the file ofthis patent UNITED STATES PATENTS OTHER REFERENCES Railway Age, Simmons-Boardrnan Publishing Co., vol. 153, No. 9, August 27, 1962, page 35. 

1. A DRAFT GEAR FOR RAILROAD DRAFT RIGGING, SAID DRAFT GEAR FITTING WITHIN THE POCKET OF A RAILROAD CAR SILL, SAID POCKET BEING DEFINED BY SIDE SILLS AND FORWARD AND REAR STOPS, SAID DRAFT RIGGING INCLUDING A YOKE FITTING AROUND THE DRAFT GEAR AND ABUTTING ON A REAR ELEMENT OF THE DRAFT GEAR AND SAID YOKE BEING CONNECTED TO A COUPLER WHEREBY THE BACK END OF THE COUPLER BEARS AGAINST AN END OF THE DRAFT GEAR IN BUFF AND WHEREBY THE YOKE BEARS AGAINST THE OPPOSITE END OF THE DRAFT GEAR IN DRAFT, SAID DRAFT GEAR COMPRISING IN COMBINATION: (A) A BOX-LIKE CENTER MEMBER INCLUDING A CENTER MEMBER WITH SIDE ARMS EXTENDING FORWARD AND TO THE REAR OF THE CENTRAL SECTION, (B) SAID SIDE MEMBERS LYING BETWEEN THE SILLS, AND THE ENDS OF SAID SIDE MEMBERS ABUTTING THE FRONT AND REAR STOPS WHEREBY THE BOX-LIKE MEMBER IS RESTRAINED FROM SUBSTANTIAL MOVEMENT; (C) AN HYDRAULIC CYLINDER IN SAID CENTRAL SECTION; (D) A PISTON IN SAID CYLINDER; (E) PISTON RODS EXTENDING TO THE FRONT AND REAR OF SAID PISTON, (F) ONE OF SAID PISTON RODS EXTENDING TO THE END OF THE YOKE AND THE OTHER OF SAID PISTON RODS EXTENDING TO THE BACK END OF THE COUPLER; (G) RUBBER SPRINGS ON BOTH SIDES OF THE CENTRAL MEMBER WITH THE PISTON RODS EXTENDING THROUGH THE SPRINGS, (H) SAID SPRINGS BEING LOCATED WITHIN THE SPACE DEFINED BY THE SIDE MEMBERS; AND (I) AN END PLATE ADJACENT THE OUTER END OF EACH OF THE SPRINGS, (J) SAID END PLATES BEING FREE TO SLIDE WITHIN THE SIDE MEMBERS BUT BEING RESTRAINED FROM MOVEMENT BEYOND THE ENDS OF THE SIDE MEMBERS, (K) SAID SIDE MEMBERS SERVING AS GUIDES FOR THE END PLATES, (L) ONE OF SAID END PLATES TRANSMITTING FORCE TO THE REAR OF THE COUPLER AND THE OTHER OF SAID END PLATES TRANSMITTING FORCE TO THE YOKE. 